1. Field of the Invention
This invention relates to pleated window coverings in general, and more specifically relates to a novel take up reel means that ensures that laterally opposed ends of a window covering remain in a horizontal plane when the covering is being raised of lowered.
2. Description of the Prior Art
Modern home construction techniques use substantial amounts of glass since home buyers like to have substantially unrestricted views of their home settings.
Greenhouses or solarium structures and are becoming increasing popular in particular; they often include glass panes positioned in horizontal, vertical, and sloped planes.
Skylights are also in great demand since they provide free lighting.
The major drawback of these glass using structures is that they suffer from the drawbacks of "the Greenhouse Effect."
The wavelength of light changes as it passes through glass; heat reflected from a surface inside a solarium, for example, cannot escape as readily as it entered because the wavelength of infrared radiation (heat) is shorter than that of visible light. Thus, the inside of a solarium is a heat trap because once the wavelength of the light has been shortened, it cannot so easily pass through the glass again.
The most popular solution to the problem has been the use of window shades in general.
The most practical type of window shade is believed to be the pleated variety; these shades reflect incoming light to substantially offset the Greenhouse Effect but they do not spoil the view because they can be drawn up whenever desired.
Moreover, they can be provided in translucent or transparent form as well to enhance the view even when they are in their lowered position.
Pleated window coverings are easier to clean than the outdated venetian blinds and their modern day counterparts which have narrower slats. More importantly, perhaps, pleated window coverings, since their accordion-like structure is a continuous, integrally formed structure, they do a better job of reflecting light vis a vis discrete slat blinds.
Unfortunately, pleated window coverings of the prior art suffer from one of the more aggravating drawbacks that afflict the discrete slat blinds: they have a tendency for their base to skew from the horizontal when raised or lowered.
This skewing is caused by uneven take up of the cord used to draw the blinds or coverings. Specifically, a take up reel in the form of a roller member is positioned at the top of the pleated window covering. One or more cords extending the length of the window covering have their top ends secured to the roller member so that as it rotates in response to drawing or lowering of the covering, the cord or cords wrap around the roller member.
The uneven raising or lowering is attributed to the different overlapping patterns that affect the laterally spaced coils, i.e., a coil on the left hand side of the roller member may experience substantial overlap with the result that a single rotation of the roller member can take up a large amount of cord due to the larger effective diameter of the roller member caused by the winding of the cord upon itself whereas the cord being wound at the other end of the roller member might experience less overlapping. Since the coiling is allowed to occur without any control means, the amount of overlapping is entirely random and a tilt of the base of the window covering as a result of different amounts of overlapping almost always occurs.
There is a need for a window covering assembly that can be raised or lowered in the substantial absence of skewing.
Another drawback of heretofore known pleated window coverings is that their track assemblies are deficient in several respects. For example, solarium structures and the like often have vertical glass sections that meet sloped glass sections; to cover such structures, a gentle curve must be formed in the track which mounts the window covering. Unfortunately, the tracks that have been developed are heavy and require special bending tools to adapt them to particular settings.
Moreover, since wheel members are generally used to rollingly engage the tracks, the art has developed means for interconnecting laterally spaced sets of track-engaging wheel members. Again, the means developed by the art have been inadequate; specifically, cloth materials are generally employed to interconnect the laterally spaced wheels, with unfortunate results.
There is therefore a need for an improved, easily bendable track and a need for an improved means for interconnecting laterally spaced track-engaging wheel members.